1. Field of the Invention
The present invention relates, in general, to a gallium nitride high electron mobility transistor and, more particularly, to a gallium nitride high electron mobility transistor, in which an inner field-plate is disposed between the gate and drain of the high electron mobility transistor, so that an electric field is distributed between gate and drain regions to reduce a peak value and to reduce gate leakage current while maintaining high frequency performance, thus obtaining a high breakdown voltage, reducing capacitance between the gate and the drain attributable to a shielding effect, and improving linearity, and high power and high frequency characteristics through variation in the input voltage of the inner field-plate.
2. Description of the Related Art
Generally, a High Electron Mobility Transistor (HEMT) is applied to a high power and high integration transistor, a switch, a power amplifier, a Microwave Monolithic Integrated Circuit (MMIC), etc. through the heterojunction of a compound semiconductor, such as gallium-arsenic (GaAs).
Further, in order to implement a high power Microwave Monolithic Integrated Circuit (MMIC), a transistor requires characteristics enabling it to operate at high power, high frequency and high temperature, and may have a high breakdown voltage using gallium nitride, which has an energy band gap wider than that of material belonging to group III-V.
In this case, in order to enhance the breakdown voltage of gallium nitride, a high electron mobility transistor employs a structure that uses a single electric field on a gate. Such a structure is adapted to form another electrode between a gate and a drain, which widens the electric field between the gate and the drain, thus reducing a peak value.
However, there are problems in that an electric field is not sufficiently distributed between the gate and drain regions of the high electron mobility transistor so that the electric field can be applied to microwaves, and in that the increment of a peak value relative to the electric field reduces the breakdown voltage. Further, there are problems in that, as gate leakage current increases, the gain of output voltage to input voltage is reduced, thus increasing power consumption and consequently increasing expenses, and the capacitance between the gate and the drain is increased, thus exhibiting limitations in high power and high frequency characteristics.